This invention relates to cathode ray tubes (CRTs), of the type having an external deflection coil for causing deflection of the beams emanating from the electron gun inside the neck of the CRT, and more particularly relates to the means for attaching the deflection coil to the CRT.
CRTs for color television are being manufactured in larger sizes than ever before, from 27 V up to 40 V ("V" conventionally indicating the diagonal dimension of the screen in inches). Such large size tubes present special problems for the manufacturer. Notable among these problems are those arising from the stresses inherent in or induced in the continuous glass envelope of the CRT during the manufacturing process.
Primarily for reasons of convenience and economy, it is preferred to attach the deflection coil to the envelope of the CRT using a mechanical clamping means. However, particularly in the larger tube sizes, it has been found that such clamping means can induce cracks in the interior or exterior surface of the glass envelope in the vicinity of the coil, leading to rejection of the tube by the manufacturer. Such rejects are particularly costly because they occur only after completion of the CRT manufacturing process. In such instances, it is generally more difficult to salvage portions of the rejected CRT for reuse than if rejection occurred earlier in the manufacturing process.